I got the same lead time in EU. Can you recommend any rack server for these? I guess they won't fit in normal 2U servers like HPE Proliant as most spec only one full width full height card as the board is double height if I understand it correctly.
I emailed the guy linked thru OP's post for VCU1525 through Avnet He said its the same price for active or passive and lead time is 4-8 weeks.
For a workable case, not sure if they ship to EU but I have two of these 6 card cases for gpus at a local my datacenter:
https://www.miningrigs.net/product/gray-matter-v3-1-gpu-case/ they have great airflow. They take up 4U of space, and some rails to sit on are sold seprately. I have a mismash of different cards and i notice the blower style cards run hotter in this than the open fan gpus, so id probably go for passive fpga and buy another of these cases for them. I would probably try to modify the airflow so it was forced to go through the cards rather than through & around, though consideration for the back of board cooling would be in order.